The present invention relates generally to cartons formed from paperboard material for packaging beverage containers such as cans, and more particularly to a method for forming such a carton for packaging the beverage cans in two or more tiers.
In modern beverage packaging, one of the most common forms of primary packaging is the drawn aluminum or steel can, most frequently holding twelve fluid ounces of beverage. Such cans include a generally cylindrical side wall with a lower end formed integrally with the side wall and connected to the side wall along a generally large radius of curvature to define a lowermost, generally circular base. The base is typically domed inwardly in its central portion for pressure resistance. An upper end is connected to the side wall, seamed thereto along a generally circular outer flange of a diameter greater than that of the base. The upper end includes a top surface recessed inwardly with respect to the uppermost portions of the flange.
It is common to market such beverage cans in secondary, paperboard packages containing a multiple of cans. Such cans are normally arranged in a single tier, with a common multiple being twelve cans, arranged in a 3.times.4 array. However, higher multiples such as 24 or more cans may also be packaged in a single carton. Especially at such higher multiples, the carton can become awkwardly large in certain dimensions, and the single-tier arrangement also leaves four of six carton sides of relatively short height for the printing of graphics.
One solution to this problem is to package multiples of cans in two or more tiers. For example, a carton of 24 cans can be arranged as two tiers of 3.times.4 arrays in vertical alignment. Such a carton has the convenient perimeter of a twelve-pack carton, but double-height graphic area on its sides.
A multiple-tier can carton is not without disadvantages, however. Modern, high-speed packaging equipment requires the loading of cartons through one or both ends of a paperboard sleeve. In many machines, this results in the sliding or conveying movement of cans as they are loaded into the carton. For multiple tiers, either the cans are moved in a stacked condition, or the cans of upper tiers must be moved over the cans of an already arranged lower tier. However, this is difficult as a result of the can construction described above, as the cans will "nest" with the base of an upper-tier can fitting within the flange of the top of a lower-tier can. This problem can be overcome by moving already-stacked cans within the packaging machine, but the can-to-can contact and relative motion between stacked cans resulting in such an approach may be objectionable.
A second solution to this problem may be had by placing a divider panel between tiers of cans so that no vertical can-to-can contact occurs. Such an approach is generally known, as discussed in U.S. Pat. No. 3,351,264. There, a formed thermoplastic divider is used. However, especially for waste disposal and recycling reasons, it is preferable that the divider be made from paperboard sheet. The disadvantage to this solution is that while the outer carton may at first be tightly wrapped about the stacked cans, over time the upper tier of cans will depress the paperboard divider panel into the recessed top panel of the lower tier of cans. This will in effect "shrink" the height of the carton contents, yielding a looser carton.
What is needed, therefore, is a solution to the problem of separating multiple tiers of cans while avoiding the disadvantages resulting from collapse of the paperboard divider panel over time into the recessed portions of the cans upon which the divider panel rests. Of course, any such solution must not unduly complicate the packaging operation or the overall carton design or function.